Baby Dragon short cycle

Grumpy_Guy

My Ruud Multi-tube is running badly. Consistent on off cycle click for call for gas 7secs later gas ignites 30secs later gas turns off 50secs later starts all over again. outside temp is -9c,



Open to ideas, this seems like a very basic system, pump runs constant, rads are hot. (any guesses on age)

Ironman

Have You Checked...

The heat anticipator in you thermostat? It could also be a weak holding coil in the gas valve.



Are you getting a full 24 volts to the valve?

Grumpy_Guy

Have You Checked...

No I have not, I will check voltage and change thermostat tomorrow. But I do have another problem with papa dragon doing the same thing but ignition is faster almost instant. Papa's pump does not normally run 24/7 but is currently with the short cycle.



567,000Btu



Yea I know there is blow back a side effect of tightening of the building and a competing  hood exhaust fan.



Is there no delta on these units, like bring boiler to temp then coast down for 20 degrees and do it again?

Ironman

Thermostat

If  you temporarily jumper "R to W" on the stat and the short cycling ceases, then the problem is the heat anticipator in the stat. If that's the case, and it's an old mechanical stat, set the pointer to a higher number. The higher the number, the longer the cycle. Should be set to cycle 2 - 3 times per hour max. depending on your system.

Grumpy_Guy

Thermostat

Ok, will try that tomorrow. (building is half hour away or I would do it now)

Ironman

Laundry Room?

If that stat is in a laundry room, then heat and vibration from the washers and dryers could also be affecting it.

Mark Eatherton

Blow back???

If what I am seeing is what I think I am seeing, you have a very good potential for carbon monoxide poisoning.



Nothing to be taken lightly. Especially if it is in "competition" with an exhaust hood.



This stuff can and does kill. Get it tested, checked and corrected before someone gets sick, or worse.





Seriously.



ME

Oak Park Electric

T stats 'n CO

Just another thought...    If Ironman's procedure doesn't change the cycling, leave the black and white wires tied together at the stat ( only during diagnosis ) and test voltage at the gas valve.  If the power at the valve is going on and off  the same as the burner, then the valve is just doing what it's told.  Then you have to follow the wiring from the valve back to the next control device upstream in the circuit and test there.  Eventually you will back track far enough to find the component that is interrupting the circuit and creating the cycling.  Remember, it could be the transformer, too. 



And, ME is absolutely right about the venting.  Atmospheric burners like this one are expected to dump a little flue gas into the room when they first start, but any prolonged back drafting down the chimney is extremely dangerous.  When any natural draft heating unit gets in a battle with a powered exhaust system, the heater will always lose.  Keep in mind that if the boiler is operating in a somewhat separated area of the building and it starts down drafting, there may not be much monoxide at first.  But as the air in that room becomes more flue gas and less oxygen, the flame will burn less cleanly and produce even more CO, further reducing the oxygen until it gets into a downward spiral that will quickly cause deadly monoxide levels.  Get a good detector or two, and try to find a way to stop the spilling.

Grumpy_Guy

Laundry Room?

No it is actually a garage/rec room, the living quarters are upstairs on the second floor. And the thermostat is in the garage. (go figure who thought this was a good idea)

Grumpy_Guy

Blow back???

Sorry for long post but people always mention the dangers, if I had my way the units would have been replaced with mod/cons already. But until that time comes I need to work with what I have.



Not to make light on Carbon Monoxide Poisoning, I'm not concern at this point.



The commercial area with the exhaust fan has been here for 25 years, a better exhaust fan with fresh air intake has been installed for the past 14 years. If there was a way to get more fresh air in the basement I would do it. But the building is downtown built on the property line attached to another building and fronts on main street. Oh and the basement is totally underground. Also even though I have started tightening up, I'm no where near sealing the building, it is over a century old with many air gaps.



This building is under a Fire and Life safety order, and no one has mention the need for CO detectors. (the sm dragon living unit has one installed by electrician ordered by me) The front building which is basement, commercial, residential starting on the second floor and includes the third floor.(and I can attest to the windows being open as it is extremely hot at the moment)



United States, approximately 200 people die each year from carbon monoxide poisoning associated with home fuel-burning heating equipment.



The use of carbon monoxide detectors has been standardized in many areas. In the USA, NFPA 720-2009,[80]  the carbon monoxide detector guidelines published by the National Fire Protection Association, mandates the placement of carbon monoxide detectors/alarms on every level of the residence, including the basement, in addition to outside sleeping areas. In new homes, AC-powered detectors must have battery backup and be interconnected to insure early warning of occupants at all levels.[80]  NFPA 720-2009 is the first national carbon monoxide standard to address devices in non-residential buildings. These guidelines, which now pertain to schools, healthcare centers, nursing homes and other non-residential buildings, includes three main points:[80]



    1. A secondary power supply (battery backup) must operate all carbon monoxide notification appliances for at least 12 hours,

    2. Detectors must be on the ceiling in the same room as permanently installed fuel-burning appliances, and

    3. Detectors must be located on every habitable level and in every HVAC zone of the building.





CO is roughly the same weight as air and distributes evenly throughout a room, so a detector can be placed at any height in any location, as long as its alarm can be heard.

Grumpy_Guy

Baby Dragon short cycle

Well I think I have found the problem, the solution should be easy enough but I need some advice.



The screw to the left of the dial post is an adjustment for the plate that acts like a thermo solenoid I think. Adjusted completely in and then some, adjusting out does nothing but inserting a screwdriver to move the plate activates the solenoid. If limit is bypassed and the boiler is called for heat it works as expected until heat is satisfied. (on when called, off when not)



I need to replace the limit, any suggestions what I should get? Also any advice on removing the probe that seems well rusted in?